Rotary grinding apparatus



March 26, 1935.

E. B. MYERS ROTARY GRINDING APPARATUS Filed Aug. 24, 1928 2 Sheets-Sheet 1 fig;

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Patented Mar. 26, 1935 UNITED STATES PATENT OFFICE ROTARY GRINDING APPARATUS Elman B. Myers, Norristown, Pa. Application August 24, 1928, Serial No. 301,804

15 Claims.

This invention relates to improvements in rotary grinding apparatus, and more particularly, to a novel design of one or more grinding elements.

Hitherto, rotary grinding devices have been characterized by a substantially massive construction of both the elements, be they both rotating, or one fixed, due to the extremely heavy stresses set up as a result of the high operating speeds. These heavy members have militated seriously against the efiiciency of these devices, generally, owing to their inflexibility and inability to be properly adjusted during operation so as to present parallel grinding faces when in 0 use.

A further disadvantage of such prior machines resides in the fact that the heavy weight coupled with the enormous friction between the mem-' bers, which friction has to be initially overcome before any substantial operation of the machine can be effected, imparts to the assembly a distinct braking action which lowers the'efliciency by increasing the power consumption and cost.

In heavy grinding apparatus of the types'derotation permitted has usually been relatively low due to the great mass of the grinding element and the resistance of the materials being treated.

It is an object of the present invention to provide an improved rotary grinding element adapted for use in devices of the types above noted.

It is a further object of this invention to provide such elements which are "substantially vibrationless and are characterized by a high degree of flexibility, whereby they are adapted to accommodate themselves to all types of grinding without involving any material difliculty 'or change in design, or material adjustment.

Yet another object of this invention is to provide an improved grinding element which is so designed and constructed as to automatically adjust itself to handle various types of materials to be ground.

These and other desirable objects, as will be set forth more particularly hereinafter, will be described in the specification and illustrated in the accompanying drawings, certain preferred constructions being illustrated in detail by way' of exemplification, but since the underlying principles of the invention may be embodied in other specific mechanical devices, it is not intended to be restricted to the ones shown, except as such limitations are clearly imposed by the appended claims.

In the drawings like numerals refer to similar parts throughout the several views, of which Fig. 1 is a plan view of an improved rotary grinding element, this view being taken substan-. tially along the line 1-1 of Fig. 2;

Fig. 2 is a cross section showing a pair of the improved grinding elements of Fig. 1 in operative relationship;

Fig. 3 is a schematic showing of the elements shown in Fig. 2 at the moment of the initial rotation;

Fig. 4 is a view similar to Fig. 3, showing the elements in their co-operative relationship while running at maximum or at working speed;

Fig. 5 is a detailed cross section of a modification of the grinding element shown in the previous figures;

Fig. 6 is a fragmentary detail of another modification of the grinding element;

Fig. 7 is a cross section of a plurality of grinding elements which are arranged as a gang of rotating elements; signed for the treatment of ores, gypsum, barytes, siliceous materials, ganister, etc, the speed of Fig. 8 is a rear plan view of a modification of the device shown in Fig. 1,-showing improved means for imparting a lateral component or swaging effect to the rotating grinding member; Fig. 9 is a side view of the member shown in Fi 8;

Fig. 10 is a cross section of a grinder of the conical rotor type, showing --the application of the principles of the present invention.

Referring now to Figs. 1 to 4, there is shown a rotor element having,a rim portion 1 provided with front and rear faces 2 and 3, an intermediate web portion 4, and a central hub portion 5. The face 2 of the element is adapted to serve as the grinding surface and may be substantially the same dimensions as the edge or rim 1, and the rear face 3 if desired. This construction, as will be readily appreciated, imparts to the rim, generally, a substantially square cross section, although this section may be varied as desired, so long as the function of the elements is accomplished.

The web member 4,as shown particularly in Figs. 1 to 5, is secured to, or formed integral with the rim and the hub 5 in such a manner as to be positioned in approximately the same plane as the grinding portion 2 of the rim element. The supporting web, being off center, with respect to the center of gra 'ty of the rim, designated generally by the line AA, there is a tendency for the rim to flex outwardly away from the plane of face 2.

This flexing action is assured by the weight and the construction of the rotor assembly of suitable materials, such as stainless steels, bronze, Monel metal and other alloys which are characterized by a marked degree of springiness and high tensile strength, as well as non-corrosiveness.

The rotating elements are adapted to be inserted in any suitable grinding machine and may be present as single individuals, or associated in any desired number. Whether acting in conjunction with a fixed member, or with other rotating members, the improved action due to the novel construction of the present invention, is fundamentally the same and will be described by way of illustration as that of two opposed rotating members.

Referring specifically to Figs. 3 and 4, when the elements are rotated by their actuating means, the rim portion 1, due to the effect of the unbalanced mass, whose effective position may be assumed to be determined by the line A-A, previously noted, is thrown inwardly as a result of the aforesaid unbalanced mass acting under the influence of the centrifugal moment imparted by the speed of rotation and by reason of the ability to be flexed out of normal alignment due to the flexure and size of spring web 4. The result of this, it is assumed, is that the top inner edge 6 of the member 1 is thrown inwardly by the combined forces above noted, and contacts with a like edge of the opposing element. This is rendered possible by the flexibility of the web portion 4 of the rotor assembly. As a specific instance of a suitable construction involving the principles of the present invention, a 4 inch rotor is provided with a rim portion substantially one-half inch on each edge, i. e., portions 1, 2 and 3, each /2 inch, and the web member 4 is substantially 0.040 inch in thickness. It will be readily observed therefore, that the mass of the rim portion 1 is infinitely great as compared with that of member 4, so that the latter has a maximum flexing action.

As the rotating elements attain maximum speed the faces 2 of the members apparently approach each other in a common plane, as is evidenced by the smoothness of the faces, due to the rotation of members 1 about point 6 as a fulcrum, being impelled therearound by the action of the mass of metal acting about point 7 as a center of mass. It will'be noted that this point, which lies on the center of gravity, line AA, is considerably outside of the plane of web mem- In the position shown in Fig. 4 the rotating elements have their web portion curved convexly due to the tendency of the heavy rim masses to accommodate themselves to each other along the plane faces 2. This results in a central space 8, which is adapted to serve as a feeding chamber for the materials fed through hollow shafts 9, or from any other suitable source. The construction just disclosed clearly indicates that by virtue of the flexibility of the web 4, taken in co-operation with the rigidity of the rim, the rotating element is adapted to accommodate itself along face 2 as a grinding element to any opposing surface. The magma of material suspended in its liquid vehicle, which is to be suitably ground, is fed to the grinding surfaces through the channel 9 above noted, or, if desired, may be introduced into the housing of the rotating elements, and forced from the outside of the rotating elements through the opposed grinding faces into chamber 8, and thence out through channel 9. The degree of fineness of the resulting product is determined by the distance between the grinding faces in their position of rest, and by the mass of metal contained in the rim. As pointed out above, the center of gravity of the rim is along the line AA, which, as shown in Fig. 2, coincides with the true center of gravity. However, where an increased grinding effect is desired, the effective pressure may be suitably varied by increasing the rim thickness along line 3-3 outwardly towards face 3, or by increasing the speed of rotation. This results in an increased pressure due to the inward component resulting from the centrifugal action and the increased mass of the rim.

The efficiency of the devices constructed according to the present invention is exemplified by the fact that in a device having the dimensions above enumerated, there was required threequarters of a horsepower to rotate the individual elements at 7000 R. P. M. giving an effective R. P. M. of 14000 for two counter-revolving opposed discs.

The old type rotors, having a rigid web of substantially the same thickness as the rim or slightly less, for the same rotation, required 7 H. P. in addition to requiring extreme mechanical pressure necessary to maintain the grinding faces in approximately their optimum co-operative relationship. The pressures necessary in such construction attain a value of as high as 1000 pounds per square inch in mills having 4 inch rotors, and as high as ten tons in mills having 13 inch rotors. Such pressures have a further disadvantage of warping the shaft supporting castings, these castings oftentimes being forced as much as oneeighth inch out of line. This disalignment of the prior art constructions is responsible for the undue amount of vibration which is characteristic of rotating grinders, and for the very poor and uncommercial colloiding results.

The present construction is substantially vibrationless at all speeds, due to the fact that the rims are self-adjusting as a result of the flexibility of the web members, so that the shafts proper are under no strains due to disalignment resulting in eccentric rotation.

As shown in Fig. the rim portions may be separately manufactured and fastened to the webs in any suitable manner as by screwing thereon, the web being provided with a thickened portion 4 having a screw 11 co-operating in a corresponding screw in the member 1a, the screws being lefthanded, where necessary, to accommodate for rotation. This construction permits the use of a wear-resistant material, such as manganese steel having suitable chemical resistance in conjunction with a web material having a greater tensile strength and therefore springiness. While a unitary web has been shown, it will be understood that a plurality of laminae may be joined together to give a desired increase in strength without increasing the weight of the web, or materially affecting the flexibility, or radial spokes or wire, or the like, backed up by a confining sheet may be used in lieu thereof. The purpose of the confining sheet is to form the feeding chamber, previously described in Figs. 2, 3 and 4.

While the inner face of member 4 forming a wall or chamber 8 has been shown as being substantially smooth, improved resultsin preliminarily reducing the materials to be ground, may

' action. Such action may be further be obtained by providing depressions or machine marks over its surface so as to permit coarse particles to be subjected to a preliminary shearing improved by subjecting the material, as it is forced outwardly from between the grinding surfaces, to the shearing action of a plurality of counter-revolving cutting edges. As shown more particularly in Fig. 6 the peripheries of the rims are preferably square cut in a milling machine, or the like, to form a plurality of depressions, 12, and intermediate teeth, 13. These teeth have edges, 14, which, being square cut, afford, when operated in conjunction with other like teeth, counter-revolving thereagainst, a distinct scissors-like action, which at the high speeds obtaining at the peripheries of the rotors, subjects any given quantity of material to a series of shearing effects before the material finally dischargesfrom the outer edge of the rotors. This modification is adapted for substantially all types of grinding, but more particularly for handling relatively coarse materials which do not respond readily to smooth grinding.

The devices described are also adapted to serve as elements for homogenizers or mechanical emulsifying means, the treated liquidsunder the high film pressures obtaining, being attenuated in extremely thin films and subjected to a shearing action.

In Fig. 7 there is shown a gang of rotors ar-' ranged in co-operative relationship. These comprise centrally disposed rotors 21, 22, mounted onv ,hollow shafts 23, 24, in the manner above described. On either side of these rotors are positioned like rotors 25, 26, mounted on hollow shafting 27, 28, which are positioned in a sleeve-like,

position about shaftings 23 and 24. Suitable apertures 23', 24' are provided in the shaftings 23,

24, to permit the feeding of material into the chambers formed between rotors 25-21 and 22-26. The several hollow shaftings are suitably supported. in bushings and connected to motors or other prime movers having the requisite horsepower. By the construction just noted it is possible to secure added economies by increasing the capacity of a given installation, which increased capacity permits a material reduction of the power necessary, which is especially suitable in handling low-grade material which does not warrant any great expense for its elaboration.

Where it is desired to secure a crushing action in addition to the normal shearing effect of rotary grinders, highlyemcient results are obtained for relatively low speed installations working at substantially 400 R. P. M; or thereabouts, by utilizing the structures shown in Figs. 8 and 9. In this construction the grinding face is substantially the same as that described in the previous figures.

n the rear of the rim portion, 30, there is provided a series of very shallow radial corrugations,

31, which have been shown in Fig. 9 as being considerably enlarged, for

the purpose of bringing out the co-operation between the several parts. This corrugated rear rim, as seen more particularly in Fig. 8, has associated therewith a plurality of spring-urged contacting rollers, 33.

stant swaging or pounding effect of the grinding face, 2, against its co-acting member, in addition to the rotary shearing effect normally incident to its rotation. As intimated above, this construction is peculiarly adapted for use of materials of relatively high resistance to grinding, such as various types of ores, siliceous materials, barytes, limestone, and'the like, and is adapted for the elaboration of low-grade materials generally, where the cost of installation and maintenance of elaborate stamping mills is a factor of major importance. This rotary stamping mill is adapted to secure improved results at aminimum of cost and expense for maintenance and repair, as well as avoiding the necessity of high-cost installations now required.

For emcient grinding, it will, of course, be understood that the peripheral speed of the rotor, as well as the weight of the rim, which factors govern the forces applied, will be varied to suit particular needs. For example, it is, of course, obvious that a soft talc-like material would require considerably less effective pressure for fine grinding than would the quartz-like siliceous materials such as are found in various ores. In,

treating a material ofthe latter type the corrugations on the rear face of the rotor may be suitably designed to give the desired pressures.

Referring now to Fig. 10, there is shown the application of the principles of the present invention to a revolving cone type of grinder. Hitherto these constructions have involved the use of massive rotors in, order to withstand the severe stresses involved. In the practice of the present invention there is provided the usual fixed mem-- ber, 35, having a conical grinding face, 36, forming a casing for the mill proper, if desired. This casing is conformed at 37 to provide an inlet for the material to be ground. The comprises a substantially flexible web portion, and an off -set rim portion, ing portion, 40. The rotor is suitably rotated by means'of a direct-connected motor, or. through gearing connected to boss 41, through shaft 42, and gearing 43. The boss, 41, may be integral with web member 38, or may be suitably secured thereto by bolt or rivets, or, if desired, may be welded. It will now be observed that when the member 39 is rotated the rim weight, indicated generally at 40, tends tothrow the grinding surface 36' of the rotary member, against the grinding surface 36 of the fixed member, as generally described with respect to Figs. 1 and 2. The grinding surface of the rotor is adapted to conform itself to the corresponding surface of the stator, due to the flexure of the web member, 38. As aresult, the construction, of the rotating cone type of mill, generally, may be considerably lightened, due to the fact that it is no longer necessary to provide the enormous castings Lformerly required to withstand the heavy stresses involved, and a further saving results, due to the smaller amount of power required to efliciently operate the low-weight device of thepresent invention.

It will now be seen that there has been provided a novel method'and a novel means of reducing thesize of solid materials to fine dimensions, as well as the emulsiflcation or homogenization of liquids. This result is secured by prorotating element a .40 39, having a dependviding and designing rotary grinders with rohereinbefore, the variations in the rim weight and peripheral speeds, increases the effective grinding capacity, permitting a marked economy in operation.

The grinding surfaces of the designs described are adapted to automatically accommodate themselves to each other due to the flexibility of the web members of the rotors, which members, by virtue of their flexibility, are adapted to take up all stresses and permit the aligned grinding surfaces to exert their optimum shearing and grinding effect. In addition to the above there has been provided a novel means of obtaining, where desired, a swaging or crushing effect in addition to a normal shearing or grinding effect.

These improvements have been described with reference to all types of rotary grinders generally, either horizontal, vertical, or conical, and, while certain specific embodiments have been illustrated and described clearly for the purpose of setting forth the principles of the invention, it is to be understood that these are given merely by way of exemplification, and it is not intended to be limited thereto except as such limitations are imposed by the appended claims.

What is claimed is:

1. A rotary grinding element comprising a hub portion, an intermediate flexible support, and a rim portion secured to the support and having a lateral grinding surface lying in substantially the same,plane as the support the center of gravity of the rim portion being displaced laterally on the opposite side of the web from the grinding surface.

2. A rotary grinding element comprising a hub portion, an intermediate flexible Support, and a detachable rim portion secured to the support, and having a lateral grinding surface lying in substantially the same plane as the-support the center of gravity of the rim portion being displaced laterally on the opposite side of the web from the grinding surface.

3. A rotary grinding element comprising a hub portion, an intermediate flexible support, and a rim portion secured to the support and having a lateral grinding surface lying in substantially the same plane as the support, the rim being adapted, when rotated, to be urged against a juxtaposed grinding surface by the combined moments of rotation of the element and the centrifugal moment imparted to its offset mass by said rotation.-

4. A rotary grinding element comprising a hub portion, an intermediate flexible support, and a rim portion secured to the support, and having a lateral grinding surface lying in substantially the same plane as the support, said grinding surface being provided with a plurality of cutting members whereby to provide a shearing action to materials issuing from the grinding surface the center of gravity of the rim portion being displaced laterally on the opposite side of the web from the grinding surface.

5. In a rotary grinding element of the type having a massive grinding rim and a flexible supporting member therefor, the improvement which comprises forming the rear portion of the grinding rim with a convoluted surface.

6. In a rotary grinder of the type adapted to exert a combined shearing and stamping action on materials being treated, the combination with a flexible grinding element having a massive rim and a lateral grinding surface onsaid rim, of a convoluted rear surface substantially parallel to said grinding surface, and spring urged members adapted to cooperate with said convollutions, whereby to impart a lateral hammering or swaging action to the rotary grinding element.

7. In a colloid mill, in combination, a pair of opposed rotary grinding elements, each element including a hub portion, an intermediate flexible support and a rim portion secured to the support and having a lateral grinding surface lying in substantially the same plane as the support, the said grinding surfaces being juxtaposed, the center of gravity of the rim portions being displaced laterally on the opposite sides of the webs from the grinding surfaces.

8. In a grinding mill for purposes described, a rotor having a grinding surface, a co-operating grinding element, and flexible centrifugal means resiliently urging the grinding surface into engagement with a surface of said co-operating grinding element.

9. A grinding mill for purposes described, comprising a casing, a shaft, a grinding rotor on the shaft within the casing, and a co-operating grinding surface, and centrifugally operated flexible means resiliently maintaining the grinding surface of said rotor in contact with the grinding surface of the co-operating element.

10. A grinding mill for purposes described, comprising a casing, a shaft, means for axial supply of material, a grinding rotor on the shaft within the casing, and a cooperating grinding element, the grinding rotor having a grinding surface, and centrifugally operated flexible means resiliently maintaining the grinding surface of said rotor in contact with the grinding surface of the cooperating element.

11. In a mill for the purposes described, the combination of a grinding rotor comprising a hub, a-relatively heavy rim and a relatively thin web connecting said hub and said rim, a grinding element carried by said rim, and a complementary element cooperating with said grinding element, the center of gravity of the mass of said rim being so disposed that upon rotation of said rotor said grinding element is moved toward said complementary element.

12. In a mill for the purposes described, the combination of a grinding rotor comprising a hub, a relatively heavy rim and a relatively thin web connecting said hub and said rim, a grinding element carried on a lateral face by said rim, and a complementary element cooperating with said grinding element, the center of gravity of the mass of said rim being so disposed that upon rotation of said rotor said grinding element is moved toward said complementary element.

13. In a mill for the purposes described,'the combination of a grinding rotor comprising a hub, a relatively heavy rim and a relatively thin web connecting said hub and said rim, a grinding element carried on a lateral face by said rim, and a complementary element cooperating with said grinding element, the center of gravity of the mass of said rim and of said grinding element being so disposed that upon rotation of said rotor said grinding element is moved toward said complementary element.

14. In a mill for the purposes described, the combination of a grinding rotor comprising a hub, a relatively heavy rim and a relatively thin web connecting said hub and said rim, a grinding element carried on an inclined lateral face by said rim, and a complementary element cooperating with said grinding element, the center of gravity of the mass of said rim being so disposed that upon rotation of said rotor said grinding element is moved toward said complementary element.

15. In a mill for the purposes described, the combination of a grinding rotor comprising a hub, a relatively heavy rim and a. relatively thin web connecting said hub and said rim, a grinding element carried by said rim, and a rotating complementary element cooperating with said grinding element, the center of gravity of the mass of said rim being so disposed that upon rotation of said rotorsaid grinding element is moved toward said 5 rotating complementaryelement.

ELMAN B. MYERS.

CERTIFICATE or CORRECTION.

Patent No. 1,995,549.. A March 26. 1935.

ELMAN BL MYERS.

It is hereby certified that the above numbered patent was erroneously issued to the inventor, said Myers, whereas it should have been recited that said Myers was assignor of one-tenth interest to Howard W; Dix, an interest to Stanton I.. McMillan and an interest to Albert P. Wolllteim, and said Letters Patent should have been issued to Myers, Dix, McMillan and Wollheim, their heirs or assigns; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of May, A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

